Hyperosmia – The Superhuman Ability To Detect Scents

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Hyperosmia is a medical condition wherein the patient has a greater than average ability to perceive and sense odors. Hyperosmia isn’t always a bonus to life. In fact, more often than not, it’s actually a bane.

Hyperosmia is a medical condition wherein the patient has a greater than average ability to perceive and sense odors. Hyperosmia isn’t always a bonus to life. In fact, more often than not, it’s actually a bane.
Castle Season 8 Episode 5 introduced us to Mia Laszlo. She was the prime witness to a murder, and a crucial part of the whole investigation, although she hadn’t seen the perpetrator’s face or heard his voice. She was portrayed as a funny, quaint little woman, and quite paranoid, who lived in an apartment where everything was clean and stink-free (OCD much?!) However, the reason she could help in the investigation was that she had smelled the killer. That’s correct. Smelled him distinctly enough to identify him. But is this even possible?

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Mechanism Of Smelling

First, we need to understand how we smell. Our nostrils have a large number of nasal hairs that help filter the air. At the back of the nose, we have the olfactory epithelium. Olfactory is the technical term for of smell, while the epithelium is the layer of tissue or skin that covers an organ. It has olfactory receptors covered by a mucous layer. Receptors are specific cells that receive signals. The receptors go up the nasal passage to a structure called the olfactory bulb, which leads to the brain.

The air contains a large number of odor molecules that are inhaled by us. These cannot just be inhaled; instead, they need to be carried to the back of our nostrils, to the olfactory epithelium. When these hit the back of the nose, they get stuck to the mucous layer and are dissolved. They then attach to the receptor cells. A biochemical reaction takes place and the signal is carried to the brain.

Bipolar <a href=
neuron Olfactory bulb olfactory epithelium nerve endings nasal cavity” class=”size-full wp-image-18940″ height=”513″ src=”https://www.scienceabc.com/wp-content/uploads/2018/05/Bipolar-neuron-Olfactory-bulb-olfactory-epithelium-nerve-endings-nasal-cavity.jpg” width=”576″/> Olfactory neurons. (Photo Credit : CNX OpenStax / Wikimedia Commons)

Each human has a large number of neurons, or receptor cells. Each neuron is a receptor for a different odorant molecule. There are a total of 350 types of receptors in humans. Since there are more than 1000 neurons, however, it stands to reason that there are multiple neurons for a particular odorant molecule. But hang on! Humans can distinguish more than one trillion different odors, yet we have only 350 types of receptors.

Confused? Well, each odor molecule can activate more than one type of receptor. Hence, even though we have just 350 types of receptors, based on the combination of which types of receptors are activated, we can distinguish very specific smells. Think of it like a piano, as explained by Dr. Charles Wysocki. The keys are the different types of receptor molecules, your fingers are the odor molecules and the sound produced is the smell you finally detect. Depending on the combination of keys that you press, the sound you produce is different. So, although there are a set number of keys, the potential sounds produced are incredibly broad. 

Also Read: Is It Possible To Smell Without A Nose?


Now let’s talk about the case of Mia Laszlo. During the process of smelling, at any stage from the generation of the signal until it is received by the brain, if the signal gets amplified, the sense of smell is heightened. Complicated? Let’s break it down. Consider an arbitrary scale of 1-10. When a person smells a flower, let’s assume the strength of the signal is 5. Now if the strength is amplified and becomes a 7, the smell would appear stronger to that person. This condition is called hyperosmia. Sounds pretty cool, doesn’t it?

This also allows the person to detect odors that a normal person would miss. How? While the exact reason is unknown, the general belief among researchers is that an odor may sometimes be too weak to actually generate an adequate response in a normal person. However, in case the signal gets amplified, it would become strong enough to be consciously detected by the person. This is supplemented by the fact that research has already proven that a person may sometimes not detect a smell consciously, but will still react to it subconsciously. 

Castle joke you barely stink that is a compliment coming from her meme
(Photo credit – Castle / ABC Studios)

Also Read: Why Can’t You Smell Perfume On Your Body When Everyone Else Can?

Effects Of Hyperosmia

Before you wish this ability for yourself or anyone else, hold your horses. Hyperosmia isn’t always a bonus to life. In fact, more often than not, it’s actually a bane. Think about it. With this condition, every odor is heightened and amplified. Every. Single. Odor. The good, the bad and the terribly stinky! Most people experience nausea, gagging, and bouts of vomiting because they are unable to handle the various smells.

Picture something as simple as meeting a person. While a normal person may not perceive any stink, a person with hyperosmia will probably detect some sort of stink or bad odor, as every person has some amount of body odor. Due to this, many of these people are not very social. Sorry to burst your bubble, but things are not all that peachy. Yes, Mia Laszlo managed to help catch the killer because of his smell, but that woman lives in a house with a disinfecting chamber at the entrance! And she is HIGHLY antisocial.

Stink what's that lord voldemort meme

Cause And Treatment Of Hyperosmia

Hyperosmia is genetically a rare condition. Very few people are born with it, but a person can also acquire it temporarily. Pregnancy is known to cause hyperosmia in many women. The degree of it may vary, but plenty of women report a marginally heightened sense of smell during their pregnancy. It goes away eventually, usually after delivery.

Another known cause is having a migraine. From those people who suffer from migraines, a number of them have also reported hyperosmia. However, the reverse has also happened. Hence, there is no credible proof as of now as to whether hyperosmia causes a migraine or vice versa. It can also be caused by exposure to toxic vapors or due to the occurrence of certain diseases. In certain instances, trauma to the nose can also result in hyperosmia. Although these factors can cause hyperosmia, they don’t always. In fact, most of the time they result in other olfactory conditions, such as a reduced ability to detect odors (hyposmia), or the loss of the ability to detect odors (anosmia).

There are very few treatment options available. Most of the time, the condition goes away on its own, like when it’s caused by pregnancy, migraine, etc. In some cases of hyperosmia caused due to disease or trauma, surgical procedures may be available, along with corticosteroids. If the condition is genetic, it is usually not treatable.

Keep in mind, however, that due to its rarity, the mystery of hyperosmia hasn’t fully been unraveled yet. Even now, very little is known about the condition. And while it may seem really nice on screen, it’s best to leave it there.

References (click to expand)
  1. How humans distinguish between smells. The University of Pennsylvania School of Arts and Sciences
  2. Humans Can Identify More Than 1 Trillion Smells. nih.gov
  3. Hummel, T., Landis, B. N., & Hüttenbrink, K.-B. (2011). Smell and taste disorders. GMS Current Topics in Otorhinolaryngology - Head and Neck Surgery; 10:doc04; ISSN 1865-1011.
About the Author

Mahak Jalan has a BSc degree in Zoology from Mumbai University in India. She loves animals, books and biology. She has a general assumption that everyone shares her enthusiasm about the human body! An introvert by nature, she finds solace in music and writing.

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